1. Field of the Invention
The present invention relates to a motor driving apparatus and method capable of effectively removing a noise signal included in a back electromotive force (BEMF) signal using a frequency of a pulse width modulation (PWM) signal, in detecting a position of a rotor using the BEMF signal, in a sensorless-type motor.
2. Description of the Related Art
In a motor driving apparatus that does not use a hall sensor, a position of a rotor may be detected using a zero crossing point of a back electromotive force (BEMF) signal. In order to detect the BEMF signal in an apparatus for driving a three phase motor, a BEMF voltage is measured in a floating phase. In this case, an output signal indicating the position of the rotor, similarly to an output signal of the hall sensor, may be obtained by using a zero crossing method of comparing the BEMF voltage rising and falling by 60 degrees with a predetermined reference voltage.
However, a BEMF signal detected by a general method may include noise due to various factors. Therefore, in the case in which the BEMF signal is compared with the reference voltage as it is, it may be difficult to find an accurate zero crossing point. Particularly, noise included in the BEMF signal may be a noise signal having a high frequency. Therefore, a method of detecting the BEMF signal that is not affected by the noise has been required.
Cited Reference 1 relates to a speed and position observer of a permanent magnet synchronous motor and discloses a method and apparatus of calculating BEMF of a motor to calculate a speed and a position of the motor. Cited Reference 2 relates to an apparatus for driving a brushless DC motor and discloses a configuration in which BEMF is detected based on a level of a voltage signal, similarly to the case in Cited Reference 1, and noise is distinguished using an amount of current in the case in which the level thereof is higher than a reference value. However, a configuration in which parameters for filtering a BEMF signal are determined by using a frequency of a pulse width modulation signal and a BEMF signal from which noise has been removed is obtained by using the parameters has not been disclosed in either of cited references 1 and 2.